Buggy code:
public abstract class EC2Cloud extends Cloud { private final String accessId ; private final Secret secretKey ; private final EC2PrivateKey privateKey ; public final int instanceCap ; private final List < SlaveTemplate > templates ; private transient KeyPairInfo usableKeyPair ; private transient Jec2 connection ; protected EC2Cloud ( String id , String accessId , String secretKey , String privateKey , String instanceCapStr , List < SlaveTemplate > templates ) { } public abstract URL getEc2EndpointUrl ( ) throws IOException { } public abstract URL getS3EndpointUrl ( ) throws IOException { } protected Object readResolve ( ) { } public String getAccessId ( ) { } public String getSecretKey ( ) { } public EC2PrivateKey getPrivateKey ( ) { } public String getInstanceCapStr ( ) { } public List < SlaveTemplate > getTemplates ( ) { } public SlaveTemplate getTemplate ( String ami ) { } public SlaveTemplate getTemplate ( Label label ) { for ( SlaveTemplate t : templates ) <START_BUG> if ( label . matches ( t . getLabelSet ( ) ) ) <END_BUG> return t ; return null ; } public synchronized KeyPairInfo getKeyPair ( ) throws EC2Exception , IOException { } public int countCurrentEC2Slaves ( ) throws EC2Exception { } public void doAttach ( StaplerRequest req , StaplerResponse rsp , @ QueryParameter String id ) throws EC2Exception , IOException , ServletException { } public void doProvision ( StaplerRequest req , StaplerResponse rsp , @ QueryParameter String ami ) throws IOException , ServletException { } public Collection < PlannedNode > provision ( Label label , int excessWorkload ) { } public boolean canProvision ( Label label ) { } public static EC2Cloud get ( ) { } public synchronized Jec2 connect ( ) throws EC2Exception { } public static Jec2 connect ( String accessId , String secretKey , URL endpoint ) { } public static Jec2 connect ( String accessId , Secret secretKey , URL endpoint ) { } public static String convertHostName ( String ec2HostName ) { } public static String convertS3HostName ( String s3HostName ) { } public static Integer convertPort ( String ec2Port ) { } public S3Service connectS3 ( ) throws IOException , S3ServiceException { } protected Jets3tProperties buildJets3tProperties ( URL s3 ) { } public URL buildPresignedURL ( String path ) throws IOException , S3ServiceException { } public static URL checkEndPoint ( String url ) throws FormValidation { } public static abstract class DescriptorImpl extends Descriptor < Cloud > { public InstanceType [ ] getInstanceTypes ( ) { } private FormValidation validateBase64 ( String value , boolean allowWhitespace , boolean allowEmpty , String errorMessage ) { } public FormValidation doCheckAccessId ( @ QueryParameter String value ) throws IOException , ServletException { } public FormValidation doCheckSecretKey ( @ QueryParameter String value ) throws IOException , ServletException { } public FormValidation doCheckPrivateKey ( @ QueryParameter String value ) throws IOException , ServletException { } protected FormValidation doTestConnection ( URL ec2endpoint , String accessId , String secretKey , String privateKey ) throws IOException , ServletException { } public FormValidation doGenerateKey ( StaplerResponse rsp , URL ec2EndpointUrl , String accessId , String secretKey ) throws IOException , ServletException { } } private static final Logger LOGGER = Logger . getLogger ( EC2Cloud . class . getName ( ) ) ; private static boolean isSSL ( URL endpoint ) { } private static int portFromURL ( URL endpoint ) { } }

Fix:
if ( ( label == null ) || ( label . matches ( t . getLabelSet ( ) ) ) )